Add List Item Counter

Add counters to list items with multiple numbering systems.

Input
List Item Separator
Split list items by a symbol.
Split list items by a regex.
Input Separator. Enter split character or regex.
Counter System
Select the numbering system.
Counter Format
Choose how the counter is displayed.
Custom format. Use %n to insert the counter.
Counter Options
Skip items that are empty.
Count items from the end of the list.
Start counting at zero instead of one.
Output Separator
Join the numbered items with this symbol.
Output

What this tool is for

Add counters to list items with multiple numbering systems.

This kind of tool is most helpful when manual editing would be slower, more error-prone, or too opaque to verify quickly.

How insertion works on each unit

Add List Item Counter inserts new content into each relevant items. Position matters here. Adding something before a line, after a line, or around a value can change how the output is read downstream, even when the original content stays intact.

List tools usually treat each line or separator-delimited value as a discrete item, so separators and blanks affect the result.

This tool is deterministic: the same input and the same settings produce the same output every time. All processing happens in your browser, so your input stays on your device during the transformation.

Where this tool earns its keep

Number lists for documents.

Create indexed lists.

Generate ordered outputs.

Examples

Quick before and after

Input
Add List Item Counter input:
Email: john.doe@example.com
Status: active

Output
Add List Item Counter output:
Email: john.doe@example.com
Status: active

Added markers become part of the output

Input
alpha
beta

Settings
Suffix: . 

Output
1. alpha
2. beta

Spacing is controlled by the prefix or suffix values.

Input expectations and common surprises

Insertion tools are literal. If spacing around the added content matters, include that spacing in the prefix, suffix, or inserted text itself rather than assuming the tool will add it for you.

For deterministic tools, the same input and the same settings should reproduce the same result. If not, the input likely changed in a small but meaningful way.

Frequently Asked Questions

Will the same input and settings always produce the same output?

Yes. This tool is deterministic, so repeating the same input with the same settings produces the same result.

Does this tool process data in the browser or on a server?

This tool runs locally in your browser, so your input is processed on your device rather than being uploaded for server-side conversion.